Division of Cardiology

Carlos Morillo


Professor (PT), Division of Cardiology, Department of Medicine






Research Interests

  • Sympathetic Microneurography
  • Baroreflex modulation
  • Heart rate and blood pressure variability
  • Linear and non-linear dynamics of biological signals
  • Plethysmography
  • Lower body negative pressure
  • Tilt table testing

The primary focus of my work is the understanding of the physiologic mechanisms that control blood pressure and heart rate during different physiologic and non-physiologic stimuli in humans. I have a particular interest in baroreflex control both at the vagal and sympathetic levels and their role during different situations such as vasovagal syncope, supraventricular and ventricular tachycardias. I also have a great interest in the role of cardiovascular reflex responses and their prognostic value in coronary artery disease, sudden cardiac death and stroke.

Specific studies include:

  1. Investigation of cardiovascular autonomic control during orthostatic stress in subjects with recurrent vasovagal syncope.
  2. Determine the role of cardiac resynchronization therapy and restoration of cardiac and vascular reflexes.
  3. Determine the prognostic value of baroreflex sensitivity, heart turbulence and T wave alternans in patients at risk of sudden cardiac death.
  4. The effects of simulated ventricular tachycardia on sympathetic and vagal baroreflex mechanisms.
  5. Investigation of the normal baroreflex and vascular response to orthostatic stress in male and female and in different age groups.

Selected Publications

  1. Taylor JA, Morillo CA, Ellenbogen KA, Eckberg DL. (1996) Higher sympathetic nerve activity during ventricular (VVI) than during Dual-chamber (DDD). J Am Coll Cadiol 28:1753-1758.
  2. Ellenbogen KA, Morillo CA, Wood MA, Gilligan DM, Eckberg DL, Smith ML. (1997) Neural monitoring of vasovagal syncope. PACE 20:788-794.
  3. Morillo CA, Jones DL, Klein GJ. (1996) Effects of autonomic manipulation on ventricular fibrillation and internal cardiac defibrillation thresholds in pigs. PACE 19:1355-1362.
  4. Morillo CA, Eckberg DL, Ellenbogen KA, Beightol L, Hoag JB, Tahvanainen KUO, Kuusela TA, Diedrich AM. (1997) Vagal and sympathetic mechanisms in patients with orthostatic vasovagal syncope. Circulation 96:2509-2513.
  5. Morillo CA, Camacho ME, Wood MA, Gilligan DM, Ellenbogen KA. (1999) Diagnostic utility of mechanical, pharmacologic and orthostatic stimulation of the carotid sinus in patients with unexplained syncope. J Am Coll Cardiol 34:1587-1594.
  6. Yoon BW, Morillo CA, Cechetto D, Hachinski V. (1997) Cerebral hemispheric lateralization in cardiac autonomic control. Archives of Neurology 54;741-744.
  7. Rudas L, Crossman A, Morillo CA, Halliwill JR, Tahvanainen KUO, Kuusela TA, Eckberg DL. (1999) Human sympathetic and vagal baroreflex responses to sequential nitroprusside and phenylephrine. Am J Physiol (Heart Circ Physiol) 276:H1691-H1698.
  8. Villar JC, Leon H, Morillo CA. (2004) Cardiovascular autonomic testing in asymptomatic T. Cruzi carriers: A sensitive method for clinical staging of Chagas’ disease. Int J Cardiol 93:189-195.
  9. Leon H, Guzman JC, Kuusela T, Dillenburg R, Kamath M, Morillo CA. (2005) Impaired baroreflex gain in patients with inappropriate sinus tachycardia. J Cardiovasc Electrophysiol 16(1):64-8.